import java.util.ArrayList;
import java.util.List;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: 26727
 * Date: 2024-06-14
 * Time: 11:15
 */
class Solution4 {
    List<List<Integer>> ret;
    List<Integer> path;

    public List<List<Integer>> subsets(int[] nums) {
        ret = new ArrayList<>();
        path = new ArrayList<>();

        dfs(nums,0);

        return ret;
    }

    void dfs(int[] nums, int pos) {
        ret.add(new ArrayList<>(path));

        for(int i = pos; i < nums.length; i++) {
            path.add(nums[i]);
            dfs(nums,i+1);
            path.remove(path.size()-1);//恢复现场 回溯
        }
    }
}